The present invention relates to a softener device for reducing water hardness, suitable for utilization in a household washing machine, in particular a dishwasher, and a relevant manufacturing method thereof.
As known, the household washing machines making use of water, in particular dishwashers, are equipped with a device for decalcifying of the washing and rinsing water, which is provided for reducing water hardness and avoid calcareous deposits. Such a device is also known as a water softener.
As known, the calcareous deposit is the result of a remarkable amount of calcium (Ca++) and magnesium (Mg++) ions contained in the wash water and from the heating produced inside the machine during washing.
Therefore, the decalcifier provides for exchanging the calcium (Ca++) and magnesium (Mg++) ions of the water entering in the wash tub with sodium ions (Na+) contained in appropriate resins, placed in the decalcifier.
The resins, or other similar matter, hereafter called resins for simplicity""s sake, become exhausted after a certain time of usage, i.e. they release their sodium ions (Na+) to be exchanged with the calcium (Ca++) and magnesium (Mg++) ions of the water; therefore when the resins are exhausted, the water flowing through the latter substantially maintain the same hardness as it had at the inlet.
The higher is the water hardness degree, the faster resin exhaustion will occur.
A regeneration stage of the resins is performed to avoid this drawback; this consists in introducing a water and salt solution (NaCl) in the resins container.
This stage is usually executed for every wash cycle, with a considerable quantity waste of salt, to be often introduced by the user; moreover, a higher water consumption is also required.
Is known that to reduce salt and water wastage, some washing machines are currently equipped with water hardness sensors, which enabling resins regeneration only upon detecting a reduction of water hardness below a certain threshold following their exhaustion.
Said sensors usually measure water resistivity and, from the results obtained, a control system will either enable or not resins regeneration.
According to this system electrodes have to be immersed in water and electrically supplied. Even in case of a low voltage being applied to the sensors, this will always entail a risk, since the sensors are in direct contact with water.
Even if a water hardness reduction is performed regularly, nothing will hinder that a light calcareous layer may deposit on the sensors, before regeneration is started, thus altering water hardness detection due to an additional calcareous resistivity.
Moreover, these systems detect water hardness directly, whereas the resin status only indirectly; as a result, the resins regeneration will be activated also in those instances where it is not yet required.
It is the aim of the present invention to solve the above drawbacks and provide, in particular a water softener device for reducing water hardness, which is suitable for the use in a household washing machine, in particular a dishwasher, wherein the detection of the exhaustion of the reducing means can be realized in a simple, easy, safe, cheaper and direct way.
Another aim of the present invention is to provide a method for detecting exhaustion of the ionic exchange resins, which is a safe and advantageous method.
Another aim of the present invention is to provide an advantageous manufacturing method of such a device for reducing water hardness.
In order to achieve such aims, it is the object of the present invention to provide a device for reducing water hardness, a detecting method of resins exhaustion and a manufacturing method of a device for reducing water hardness, having the features of the annexed claims, which form an integral part of the present invention.
Further aims, features and advantages of the present invention will become apparent from the following detailed description and annexed drawings, which are supplied by way of non limiting example, wherein: